Power transmission



Aug. 29, 1939. F. s. HODGMAN 2,171,177.

POWER TRANSMISSION med Aug. 25, 1936 2 Sheets-Sheet 1 v 'INVENTOR FREDERICK 5. Housman BYWLW ATTORNEY Patented Aug. 29, 1939 rowan TRANSMISSION Frederick S. Hodgman, Glen Rock, N. J., assignor,

by mesne assignments,

to The Waterbury Tool Company, Waterbury, Conn, a. corporation of Connecticut Application August 25, 1936, Serial No. 97,791

. 7 Claims. (01. 255-19) This invention relates to power transmissions and particularly to'transmissions of the hydraulic type. comprising a fluid pump and fluid motoreither or both of which may be provided with mechanism for varying its displacement in order to vary the speed ratio between the prime mover which operates the pump and the load device which the motor operates. The invention is illustrated as adapted for use in a well drilling rig of well-known type in which a string of drill stem is caused to revolve by a rotary drilling head while a portion of the weight of the string rests upon the earth formation at the bottom of the hole being drilled, the remainder being suspended on a block and falls mounted in a drilling derrick and connected to .a'draw-works drum.-

It is desirable in such drilling operations to maintain at a constant value that portion of the weight of drill string which rests upon the earth formation at the bottom of the hole and to-be able to readily adjust such weight to diflerent values as different formations are encountered. Various systems have been proposed for automatically regulating the weight on the drill stem in such a manner. Systems of this character as heretofore constructed have utilized either the energy of the drill stem itself for-feeding the same into the hole as required; such, for example, as systems wherein a friction or fluid brake is automatically regulated to maintain a constant tension on the draw-works drum, or have utilized an expensive and cumbersome power operated feed system such-as a steam or electric powered feed controlling apparatus. Devices of the lat- 85 ter class are not only expensive in first cost and in operation but are open to other objections in that they require specially trained operators or are incapable of use in fields where an adequate water supply is not available.

It is an object of the present invention to provide a well drilling rig whereby the weight of the drilling bit on the earth formation at the bottom of the hole may be maintained at a constant but adjustable value and which incorporates simple, reliable and inexpensive apparatus capable of operation in any locality by untrained operators.

A further object is to provide a well drilling rig of this character including a feed controlling device which may be energized from a small prime mover independently of the principal source of power for the draw-works and other apparatus usually associated with drilling rigs of the rotary type and which small prime mover may 65 preferably comprise a small internal combustion engine of the type used in motor vehicles which are readily available at low cost.

It is a further object to provide a feed controlling apparatus for a well drilling rig wherein a hydraulic variable speed power transmission is 5 incorporated for transmitting power between a substantially constant speed prime mover and the draw-works drum, whereby the speed of' rotation of the drum may be precisely controlled automatically to maintain a predetermined constant weight on the drill bit and whereby also the draw-works may be operated from the auxiliary prime mover to raise or lower thedrill string in an emergency.

Further objects and advantages of the present 15 invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of the present invention is clearly shown. 7

In the drawings: 20

Fig. 1 is a plan view partly in section of a well drilling rig showing a preferred form of the present invention.

Fig. 2 is a cross section on line 2-2 of Fig. 1.

'Fig. 3 is a cross section on line 33 of Fig. 1. 25

Fig. 4 is a fragmentary detail view of a por tion of the apparatus.

Referring now to Fig. 1 there is illustrated a draw-works having a drum l0 journalled in bearings i2 and adapted to have wound thereon a 30 cable by which a drilling string may be supported from a derrick, not shown, in the usual manner. The drum. it is keyed to a shaft i l on' which is splined a slidable clutch member it which may be engaged with a sprocket i8 freely rotatable 35 on the shaft I4. At its opposite end the shaft i4 carries splined thereon a slidable clutch member 20 engageable with a gear 22 freely rotatable on the shaft it. The sprocket l8 is driven by a chain 24 from a suitable prime mover, not'shown, 40 through the medium of any suitable multiple speed transmission mechanism. The sprocket l8 -carries a hub 26 on which is splined a slidable clutch member 28 engageable with a sprocket 30,

freely rotatable on the hub 26. The sprocket 3|! 5 drives by means of a chain 32, a sprocket 34 keyed to a shaft 36 which carries a bevel pinion 38 meshing with a bevel gear on the under side of a rotary table 40 whereby the drill stem may be given 'a rotary movement independent of the 50 vertical movement imparted to it by the drawworks drum III, as is well-known in the art.

. The gear 22 is adapted to be driven from a fixed displacement fluid motor 42 through the medium of a pinion l4 and intermediate gearing III) 48. The motor 42 is connected by means of a high side conduit 48 and a low side conduit 50 with a variable displacement fluid pump 52 which has its input shaft 54 connected by means of reduction gearing 56 to the crankshaft of an internal combustion engine prime mover 58.

The pump 52 and motor 42 are illustrated as of the well-known Waterbury construction as shown in Fig. 2. The pump 52 includes a revolving cylinder 60 within the bores 62 of which pistons 84 are reciprocated by the motion of a socket ring 68 which revolves in a tilting box 68. The tilting box 88 carries a stud I0 having a pivoting and sliding connection with the piston I2 of a fluid motor I4; The socket ring 66 is caused to revolve with the shaft 54 by a universal joint connection, not illustrated, while the cyl-' inder barrel is keyed to the shaft 54. The tilting box 68 is mounted for oscillatory movement on trunnions IS in the casing 18 of pump 52.

When the tilting box 88 and consequently the socket ring 86 are tilted about the trunnion I6 and shaft 54 is caused to revolve, the pistons 84 are reciprocated in the bores 82 due to the inclination of the plane of rotation of the socket ring 86 to the plane of rotation of the cylinder barrel 60, the stroke of the pistons 84 being determined by the angular setting of the tilting box 88': As pistons 84 are reciprocated, fluid is caused to be drawn into the cylinders 82 through one arcuate port, not shown, in the valve plate 80 and to be expelled from the cylinders 82 through the opposite arcuate port in the valve plate 80. Customary replenishing and relief valves, not shown, are incorporated in the valve plate 80 for the purpose of maintaining the working circuit filled with fluid at all times and for preventing building up of excessive pressure and undue overloading of the" machine.

The fluid motor 42 is similar in construction to the pump 52 except that its socket ring is journalled in a fixed angle box so that the stroke of its pistons is fixed. Fluid delivered from the pump 52 through one of the ports of the valve plate 80 and through conduit 48 is admitted to the cylinders ofthe motor 42 through arcuate port 82 in the motor valve plate 84, while on the return stroke of the pistons of the motor 42 fluid .is returned to the pump through port 86 of motor valve plate 84 and through low side conduit 50 to the opposite arcuate port in the valve plate 80. The construction and operation of hydraulic transmissions of this character are well-known in the art so that further description thereof is unnecessary.

The valve plate 84 is provided with conduits 88 and 80 forming a by-pass from the high pressure port 82 to the low pressure port 86 which is under the control of a valve 82 operable by means of bevel gearing 94, shafts 85, bevel gearing 91 and handwheel 98 from a position adjacent the drillers post.

The fluid motor I4 includes a cylinder I 00 .within which is freely reciprocable a piston I02 mounted on the piston rod 12. A conduit I 04 connects the left-hand end of the cylinder I00 with the high side conduit 48. At the opposite end of the piston rod 12 a guide piston I 06 is formed, against which abuts a spring I08 which is adjustable by means of a spring plate H0 and adjusting screw H2. The latter is operable by means of bevel gearing II4, shaft II 8 and handwheel II8 from a position adjacent the drillers post.

Adjacent the periphery of the gear 22 a locking detent I20 is pivoted at I22 and carries a lever I24 to which is connected a piston I26. Piston I 28 is reciprocable in a cylinder I28 having its lower end connected by a conduit I30 to the high side conduit 48. A spring I32 biases the piston I28 downwardly, and consequently urges the detent I20 into gear-engaging position whenever pressure in the conduit 48 is insuflicient to overcome the force of the spring I32.

In operation assuming the drill string to have been run into the hole, and the apparatus arranged for drilling operation; the clutch member I6 having been adjusted to disengage the sprocket I 8, the clutch member 20 having been engaged with the gear 22, and clutch member 28 having been engaged with sprocket 30, the rotary table is driven from the principal power source of the.

drilling rig through chain 24, sprocket I8, clutch 28, sprocket 30, chain 32, sprocket 34, shaft 36 and pinion 38. With the prime mover 58 running at a substantially constant speed the pinion 44 will be caused to turn at a speed determined by the position of the tilting box 68, which is in turn governed by the position of the piston I02. Assuming the drill string to be lowered sufliciently so that its entire weight rests on the bottom of the hole, the spring I08 will urge the piston I02 to the left in Fig. 2, thus moving the tilting box 68 into stroke in a direction causing drum I0 to rotate in the hoisting direction.

As soon as the weight of the drill string comes on the drum I0, a resisting pressure is built up in the conduit 48, which pressure is transmitted through the conduit I04 to the cylinder I00 and piston I02. Depending on the adjustment of the screw II 2 and the valve 92, the piston I02 will begin to move to the right in Fig. 2 when a certain portiori of the weight of the drill stem is suspended on the drum I0. I'he exact weight which it is desired to support during drilling operations may be determined by suitable adjustments of the amount of opening of valve 92 and of the spring force of spring I08. Under certain conditions it is desirable to operate with the pump 52 having its tilting box maintained in a substantially I neutral position so that as fast as the drilling bit makes hole, the weight of the drill string causes the motor. 42 to operate as a pump, the entire output of which is passed through the by-pass 88-90. For this purpose an indicator I38 .is pivoted on a bracket I40 to move over a scale I42. One end of the indicator I38 is connected to an extension rod I44 passing through the end wall of the cylinder I00 and connected to the piston I02. By observing the position of the indicator I38 the operator may adjust the opening of the valve 92 so that the piston I02 rests in midposition wherein'the tilting box 68 is at no stroke. Should the bit make hole at a faster rate the increased weight on the drum I0 causes the pressure in conduit 48 to rise, thus moving piston I02 to the right and causing fluid to be pumped by pump 52 from conduit 48 to conduit 50 at a slow rate. The motor 42 is thereby permitted to turn faster to make. up for this quantity which formerly went through by-pass 88-90. Conversely, if the bit makes hole at a slower rate, the pressure falls slightly in conduit 48 causing piston I02 to move to the left and add a small quantity to the fluid pumped into conduit 48 by motor 42. Since by-pass 88-90 is the only path from conduit 48 to-conduit 50, the motor 42 will be slowed down to permit the additional fluid from pump 52 to go through the by-pass.

The weight maintained on the drilling bit may ment of the weight supported may'be obtained be read from the usual weight gauge, not shown.

or'from a pressure gauge I48 in the line I80; This weight may be varied by varying the adjustment of the spring I08 by means of the handwheel II8.

Should it become necessary for any reason such as failure of'the principal source of power to lift the drill string by means of the auxiliary prime mover 58, this may be done by closing the valve 92 and by tightening the adjustment of the spring I08 suiiiciently so that it exerts a force to the left greater than the force exerted on the piston I02 when the entire weight of the drillstring is suspended by the drum I0. Under these conditions the piston I02 moves to the left, throwing the tilting box 68 into stroke in the hoisting direction and the drill string is then lifted at a rate determined by the setting of the adjusting screw I I2 in.

relation to the weight of the drill stem.

Under other conditions it may be desirable to .operate with the by-pass 88-80 completely closed.

A constant weight may be maintained on the drilling bit under these conditions by suitable adjustment of the screw I I2 such that the piston I02 is permitted to move to the right-of mid-position sufilciently to place the tilting box 88 in stroke in a lowering direction and to feed the drill stem downwardly at a rate corresponding to the rate at which the hole is being.drilled. Under these .0011! ditions also, the feed is varied automatically to follow exactly the rate of drilling. Should the drill be fed downwardly too fast, a greater proportion of the weight of the drill string would be supported on the earth so that the pressure in conduit 48 is decreased, thus permitting piston I02 to move to the left reducing the rate of downward feed until a stable condition is reached. Likewise, if the downward feed be too slow for the rate of drilling, a greater proportion of the weight becomes suspended on the draw-works drum I0 so that the pressure in conduit 48 is increased,- thus moving the piston I02 to the right and increasing the rate of downward feed correspondingly.

Should a failure in the prime mover occur at any time or should any accidents befall the hydraulic transmission so that pressure cannot be maintained in the conduit 48, the spring I32 is permitted to expand, moving the detent I20 into engagement with the gear .22, thus preventing the drill string from dropping into the hole causing a twist-off or other serious difliculty.

It will be noted that with anygiven setting of the adjusting screw I I2 the rate of feed and the weight supported may be adjusted over a limited range by changingthe setting of the by-pass valve 92. The spring I08 being of finite length will exert slightly less force when it is extended than when it iscompressed' due to the well known relation between force and displacement of such a spring. If, then, the by-pass valve 02 be opened wider, the piston will have to move to the left thus permitting spring I08 to expand somewhat thereby decreasing the pressure to which motor M regulatesthe pump 52. Conversely, if the bypass valve 92 be further closed the piston I02 will have -to move to the right thus increasing the pressure in conduit 48. In practice, the length of mal operation at any one setting. The adjustment of by-pass valve 92, however, provides a convenient means whereby a liner or vernieradjustwhen desired.

While the form of embodiment of the invention as herein disclosed, constitutes a' preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a well drilling rig the combination of av posed on the drum bythe drill string, means whereby said controlling member may vary the speed ratio of the power transmission, and means including a restricted, adjustable by-pass from the high to the low side of said transmission for varying the weight supportable from said drawworks drum.

2. In a well drilling rig the combination of a drill string, a draw-works drum, a prime mover, a variable speed power transmission including a variable displacement pump and a fluid motor operable thereby connected in driving relation between the prime mover and the draw-works drum, a controlling member movable in accordance with variations in fluid pressure produced by changes in torque imposed on the drum by the drill string, means whereby said controlling member may vary the speed ratio of the power transmission, and

means responsive to pressure failure in the high side of said transmission for preventing unwinding movement of said draw-works drum.

3. In a well drilling rigthe combination of a drill string, a draw-works drum, a prime mover, a variable speed power transmission including a variable displacement pump and a fluid motor operable thereby connected in driving relation between the prime mover and the draw-works drum, a controlling member movable in accordance with variations in fluid pressure produced by changes in torque imposed on the drum by the drill string, means whereby said controlling member may vary the speed ratio of the power transmission, means for looking said draw-works drum against retrograde movement and means eflective while normal operating conditions prevail for holding said last means inoperative.

4. In a well drilling 'rig the combination of a drill string, a draw-works drum, a prime mover,

a variable speed power transmission connected in driving relation between the prime mover and the draw-works drum, means responsive to varia I tions in torque imposed on the draw-works drum for controlling the speed ratio of the power transmission to feed the drill string downwardly at a rate to maintain a'constant proportion of its weight suspended by the draw-works drum, means for locking said draw-works drum against retrograde movement and means effective while normal operating conditions prevail for holding said last means inoperative.

5. In a well drilling rig the combination of a drill string, a draw-works drum, a prime mover,

a variable speed power transmission including a variable displacement pump and a fluid motor operable thereby connected in driving relation between the prime mover and the draw-works drum, means responsive to variations in torque imposed on the draw-works drum for controlling the speed ratio of the power transmission. to

feed the drill string downwardly at a rate to maintain a constant proportion of its weight suspended by the draw-works drum, and means responsive to pressure failure in the high side 01' said transmission for preventing unwinding movement of said draw-works drum.

6. In a well drilling rig the combination of a drill string, a draw-works drum, a fluid motor operatively connected to said drum, means for by-passing a variable predetermined quantity of fluid from the high to the low side ,of said motor when a predetermined unwinding torque is exerted on said draw-works drum by said drill string, and means for maintaining a constant pressure on the high side of said motor. 1

7. In a well drilling rig the combination of a drill string, a draw-works drum, a fluid motor operatively connected to said drum, means for by-pmsing a variable predetermined quantity of I fluid from the high to the low side of said motor when a predetermined unwinding torque is exerted on said draw-works drum by said drill string, and means including a pressure controlled variable displacement pump for maintaining a constant pressure on the high side of said motor.

FREDERICK S. HODGMAN. 

